I had phone screen with Facebook for E6 role for Menlo park. I have 14+ yoe - Friend referred me for this open position.
Phone screen was quite straight forward and easy. Interviewer was very friendly. I had 1-Easy and 1-Medium problem to solve.

I had 45 mins discussion:
3-4 mins - introduction
15 mins - First question - Easy - https://leetcode.com/problems/maximum-subarray/
15 mins - second question - Medium - https://leetcode.com/problems/next-greater-element-ii/
5 mins - I asked few questions about role.
We had five mins left she asked me https://leetcode.com/problems/next-greater-element-i/ - she just wanted to know the approach. I provided Hashmap and stack solution and she was satisfied with the approach.

Preparation:
By the time Facebook interview was lined up I almost covered near to 400 problems on LC and 100 on other platforms.
For this interview I just went through top 100 Facebook tagged problems on LC (both the questions asked in this discussion were not in top 100 :( but both were very basic so was able to solve them quickly).

Hope this helps people preparing for Facebook Phone screen... Happy coding :)